node.js error when starting app

I use ubuntu server with installed npm. I tried run this app for practice.

When i run node app.js into /project/socket_server/ i get this errors

root@root:/var/www/SynergyTube/socket_server# node app.js

node.js:201
        throw e; // process.nextTick error, or 'error' event on first tick
              ^
TypeError: Object #<Object> has no method 'existsSync'
    at Object.<anonymous> (/var/www/SynergyTube/socket_server/first_start.js:2:8)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)
    at Module.load (module.js:348:32)
    at Function._load (module.js:308:12)
    at Module.require (module.js:354:17)
    at require (module.js:370:17)
    at Object.<anonymous> (/var/www/SynergyTube/socket_server/app.js:1:63)
    at Module._compile (module.js:441:26)
    at Object..js (module.js:459:10)

Can someone explain what i do wrong? Thanks